


The greatest team up of the century!!!

by what_a_mood



Category: Percy Jackson and the Olympians - Rick Riordan, The Avengers (Marvel Movies), The Heroes of Olympus - Rick Riordan
Genre: Crossover, F/M, M/M
Language: English
Status: In-Progress
Published: 2018-10-25
Updated: 2018-10-30
Packaged: 2019-08-07 09:19:41
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 4,610
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16405646
Author URL: https://archiveofourown.org/users/what_a_mood/pseuds/what_a_mood
Summary: The Avengers and demigods become allies and are shown around CHB and Avengers Tower. Lots of stories, fighting, and pranks ensue.**ON HIATUS**sry guys I'll be back soon





	1. New friends

**Author's Note:**

> hey guys. thanks for reading this. it's one of my first works, so feedback and constructive criticism is much appreciated. Sorry if it's really bad, and hope you like it!
> 
> p.s. updates might be unreliable, sorry. im a bit busy so I'll write when I can.

**Tony**

 

Tony knew Clint was in the vents. Clint always thought that he didn't, but he didn't have a multi-million dollar AI installed in his tower to not know that his teammate was crawling around in there. He knew exactly where Clint was, which was why he was strategically locking all of the vents around him so that he couldn't get out. Clint would be stuck in there until he found a way to get past the metal grates that are the entrances to the vents.

"Serves him right for trying to prank us again," muttered Tony as he watched Clint try to get out through his camera system.

Tony really didn't know why Clint was up there  _now_ of all times. Fury had called the entire team for a meeting and personally, Tony really didn't want to get on his bad side. Who knew a one eyed stare could be so _menacing_. Anyway, Steve, Bruce, Natasha, Thor and him were sitting in the briefing room waiting, and Clint was stuck above them, so they were technically all there. No reason for scary pirate Fury to get mad. Or so Tony hoped.

Just as he was thinking this, Fury stalked into the room, with his whole badass trench coat and eyepatch look going full swing. 

"Where's Clint?" he asked.

Noiselessly, Tony pointed up. Fury cast a glance at Natasha, who stood up with a smirk. She quietly got out a gun and shot five or six times at the ceiling around Clint. A muffled scream sounded from above. Tony unlocked the vents and the team watched as Clint climbed out of the grate.

"What the fuck guys!?" Clint shouted, "you could have hit me!"

"Natasha was the one shooting," said Steve, finally looking up from his book, "there's no way she would have missed her shots."

Clint sat down, grumbling to himself, between to a quietly shaken Bruce Banner and a still smirking Natasha.

 

"Ok, now that we're all here," said Fury, "I have an announcement."

Everyone looked at him silently. Thor swung his lazily swung his hammer.

"We have a new set of allies." 

Fury pressed a button and a series of pictures came up on the screens around them. They were of a set of kids aged between 13 and 19 years old. There seemed to be some different groups in the photos. There was a big group of teenagers in orange shirts standing together, a larger group of people in purple shirts and what Tony thought was Roman armour, which was weird. There was also a group of girls in silver, some of whom were holding bows and arrows, and some other girls with a woman in front of them wearing a thick gold belt. Tony thought he could see a guy with a metal collar in the background.

There were also single shots, of a green eyed, messy black haired boy; of a blond, curly haired girl with piercing grey eyes; a girl with choppy hair and kaleidoscope eyes who was pictured with a guy with neat blond hair, electric blue eyes and glasses; and many more.

"Who are these?" asked Bruce, "are we teaming up with them? They're kids... why are we so interested in them?"

Tony nodded. "He's right. We're Earth's mightiest heroes. Why do we need them?"

Fury seemed to be choosing his next words. "You're right," he said, "they are just kids. But they are very special. Some of these teenagers are more powerful than the whole team on their own. I think Thor knows them as well."

Thor did seem to be quite excited. "That's Percy Jackson! And Annabeth Chase! Those are the Heroes of Olympus!!" He bounced around in his seat. "Are we meeting them?"

"I'm sorry, but who are these? Why is Thor fangirling over them and how could  _they_ beat  _us_? We're  _us_!" Tony exclaimed.

Fury sighed. "Well I don't know everything, but here's some information."

He handed out files to the group. Natasha and Clint picked one up and started reading.

"Wait..." Clint said slowly, as he read, " _Demigods??_ These kids are Asgardian?"

"No, not Asgardian demigods, they're Greek," said Steve as he read through a file marked Camp Half-Blood.

"There are  _Greek Gods_ _?!_ What?!! And these are their children?!" shouted Tony, "And Thor  _knew_ about them and didn't tell us? And do they have powers? And how do we not know about them? And how does Fury know about them? And -"

"Stop!" yelled Bruce, looking slightly green around the gills. "Repeat but slower. I want answers as well."

 

Fury groaned. "I only know whats in those files. Thor can answer all of your questions. As for why I know, I just got told by the gods themselves. They want us to team up with the demigods for something."

Natasha nodded. "Thor, who's Percy Jackson?" she asked.

Thor smiled. "He's the only son of Poseidon. He's the most powerful out of all the demigods and he's been the child of the prophecy  _twice._ He has these cool powers and he's been to Camp Half-Blood and Camp Jupiter and Rome and  _Tartarus..._ Anyway, he's the biggest hero of them all. Thats him." He pointed to the black haired guy on the screen.

Everyone looked confused.

"I think we need the whole story Thor," said Clint. Steve nodded, looking confused.

"Ok, so when Percy was 12, he got attacked by a fury, which is a minion of Hades and...

 

***spongebob thing* 1 hour later**

 

 

...so Gaea was defeated and Leo came back with Calypso but she broke up with him and is doing college in New Rome, and everyone else is just living their lives."

"Wow." said Tony, "That is so cool."

" _Cool???!!_ That kid went to hell and back! Those are children! That's barbaric, they shouldn't have to go through all that!" shouted Steve.

"I agree," said Bruce. Clint nodded. 

"Yeah I know, but the powers are soooo cool" said Thor. Tony nodded vigorously.

"So," Fury said, "we're going to meet them tomorrow for a tour of CHB and then they'll be taking a tour of Avengers Tower. None of you can tell anyone about who they really are. They need to stay secret. Be ready at 10am and read up on those files today."

He swished out of the room.

 

"Ok, let's get ready for the greatest team up of history!!!" exclaimed Tony. He grabbed some of the files and ran to the elevator. Thor followed. The other Avengers sat reading as the two fanboys gushed about the demigods and their powers until they got into the elevator.

"Well this'll be fun." said Steve.

 


	2. An important announcement

**Notes for the Chapter:**

> hey guys, I forgot to mention this, but this is set before Trials of Apollo (or maybe we're just saying that that never happened idk yet) so there is no mention of that in this fic.
> 
> thanks for the feedback, it's really nice to see people liking the story and looking forward to updates

**Annabeth**

 

Life was good at Camp Half-Blood. Leo was back, Thalia was visiting, the Romans had agreed to stay for a while, and there were _no_  quests. It was just a quiet life of teaching the new campers, hanging out with her friends, and going on dates with Percy for Annabeth. She'd had enough quests for a lifetime. So had Percy and the rest of the seven. 

Just as she was thinking this, Annabeth saw Jason and Piper walking over to the beach where she sat, watching Percy in the water. They came over and sat down, talking quietly to each other.

"Hey Annie," said Piper, "we were just going to go out to the movies. We were thinking maybe a double date with you and Percy would be cool. Wanna come?"

"Sure, I'd love to," replied Annabeth, "let me just get Percy."

She grabbed her Yankee cap and threw it as far as she could into the lake. A second later Percy burst out holding it. He swam to the shore and got out of the water perfectly dry. He handed her back the hat and sat down on the sand.

"Hey guys, what's up?" he said, taking an apple out of Annabeth's bag and crunching into it. 

"Oh, we were just asking Annabeth if you'd like to go on a double date with us to the movies," responded Jason, who was somehow managing to sit up straight and have perfect posture even though they were on a  _beach._ Romans are weird, thought Annabeth.

"That sounds great," mumbled Percy, biting on his apple.

 

Just then, a newbie camper came running towards them over the sand, tripping and stumbling as he went.

"Hi," he said breathlessly, putting his hands on his knees as he got to where they were sitting, "Chiron wants you at the Big House. He says it's urgent, and that he needs the seven, Thalia, Reyna, Rachel, Nico and Will and if you see any of them that you should bring them with you."

"Well, that sucks." said Piper, "we were just going to go out of Camp."

The four campers stood up, brushing the sand of their clothes and picking up bags. 

"Ok, guys. Let's go see what this 'urgent' meeting is about" said Percy, already thinking about the snacks in the meeting room.

They walked off, leaving the still slightly wheezing newbie to jog after them.

 

Once they were all at the meeting room, Chiron started talking. Of course, no one could hear him over the Greeks laughing and talking and eating snacks. The Romans sat across the table from them, Reyna, Frank and Hazel all slightly wide-eyed at how the Greeks responded to 'urgent' meetings. Chiron sighed, pinching the bridge of his nose. 

"QUIET!!" he yelled, blasting an air horn into the room. The Greeks composed themselves, Leo still laughing in the background at one of Percy's jokes. Annabeth shook her head at them.

"Alright," Chiron continued, quieter now. "This meeting is to discuss a new message from the gods."

Everyone sat up straighter. A message from the gods was rare at the best of times, and after the war almost none of the gods had been communicating with their children.

"What was it?" asked Percy apprehensively. Annabeth knew that most of the messages he had got from the gods hadn't been pleasant for him.

"Everyone here knows that the Greeks, Romans, Norse, and Egyptians are allies, right?" asked Chiron.

"Please tell me there's not another set of gods," muttered Nico.

"No Mr di Angelo, there's not," replied Chiron, somehow managing to here Nico with his radar horse hearing.

"So what's happening?" asked Reyna.

"We  _do_ have a new set of allies, but they're not demigods. They're mortals."

"Wait,  _what??!_ Why are we teaming up with mortals? Do they know about us?" exclaimed Annabeth in shock. Everyone else started yelling their questions as well. Chiron waited until the noise died down and then addressed Annabeth.

"Their leader has been told about us by the gods, and has been instructed to only tell his team what he knows. They are very special mortals. They call themselves 'Earth's Mightiest Heroes'."

Leo gasped. "Are we teaming up with the Avengers??!! Do we get to meet Tony Stark?" he asked excitedly.

"We will be meeting them tomorrow for a tour of camp and then their base and-"

"Wait, wait, wait. Hold up," Percy put his hand up as a stop sign. "Tell me again who these Avengers are?"

"Their only the coolest mortals ever! How do you not know them? They saved the world last year. Big portal opened up above New York and aliens came out, and then the Avengers defeated them," Leo said loudly.

"They have an archer too," added Thalia.

"And a badass red-head assassin," said Reyna.

"And a scientist," Rachel put in, "and he can turn into a green giant!"

"Isn't he also a doctor?" asked Will.

"Anyway, they live in Stark Tower, because Tony Stark's in their team, and he's the best inventor in the world, and he's like a  _billionaire!_ " Leo rambled on.

"That is correct, Leo," said Chiron, taking control of the situation again. "We will be meeting them tomorrow, as I said, and one of you will be showing them around camp. I think Annabeth should be their guide, as she's been here the longest."

Everyone nodded, Leo looking slightly despondent.

"Of course, you'll all get to meet them. They have some information of all of you, so I suggest you research a bit about them, especially if you don't know them." Chiron looked at Percy. He groaned.

"Right, that's it. You may all go back to your activities. See you all tomorrow at 10:00." Chiron wheeled himself out of the room.

The demigods left, eating the snacks that they'd stolen from the meeting and talking about their new allies.

Annabeth left with Percy, Piper and Jason. They still had time for a double date, and Annabeth definitely wasn't missing that.


	3. Special Agent Percy

**Percy**

 

Percy watched as Annabeth waited for the Avengers. She may have seemed calm and put together to any outsider, but Percy could see how nervous she was. She was subtly fiddling with her Camp Half-Blood necklace, and her eyes darted around every so often, checking if they were here yet. He wished he could go and help her, but he'd been ordered to stay back, they didn't want to make a scene by having all of them there at once, so Annabeth was waiting outside Stark Tower, at a cafe across from it, while Percy and everyone else watched from various points around her or from the Argo III, Leo's newest project - a new Argo II, with even more gadgets and parts than before. He'd started building it almost as soon as he got back from Ogygia. Personally, Percy thought he might have built it to distract himself when Calypso broke up with him. But he wasn't about to mention that.

They'd been waiting for 20 minutes now. Percy was getting impatient. Although at first he'd felt like a secret agent, waiting outside the tower and watching everything that was going on, now he was just bored. Stark Tower was right there. They'd gotten here at 10:00 from Long Island. Percy was sure that the Avengers could step outside on time if they could do that. 

 

Percy was just trying to catch Annabeth's eye to ask if she was ok when he saw a man he recognised as Steve Rogers step onto the street. Natasha Romanoff followed with Clint Barton. Percy sat up straighter and then remembered he was supposed to be being inconspicuous, and slouched back into his chair again. Captain Rogers walked leisurely across the road and sat down across from Annabeth.

Percy saw them exchange words for a couple of seconds and strained to hear what they were saying. Annabeth nodded and Rogers made a small hand gesture. Percy wouldn't have been able to see it if he wasn't looking. Immediately, Romanoff and Barton started walking over. Percy saw Tony Stark and Dr Banner come out of the building as well. Thor came out a moment later. They all walked over to Annabeth and pulled up chairs around her table. Annabeth finally caught Percy's eye and nodded.

He got up and walked over to the group. Piper, Rachel, Reyna and Thalia, who were sitting nearby, came over as well.

"Morning," said Percy, going for the casual look as he sat down, "I'm Percy Jackson."

"Steve Rogers, nice to meet you," said the captain, holding out his hand for a handshake. He reminded Percy of the Romans, with their military feel.

Thalia and the other girls sat down.

"I hear you do archery," said Thalia to Clint. "I'm Thalia. I'm the leader of a bunch of archers. How good are you?"

She and Clint delved into a conversation about fletches and nocks, how the wind affects something, and other things that Percy didn't know about.

"I'm Piper," said Piper, "and this is Rachel and Reyna."

Stark, Banner and Romanoff introduced themselves. Thor nodded. He seemed a bit fidgety. Percy hoped he didn't have ADHD or something, because another one like them could mean chaos.

 

"Alright, shall we get going?" asked Annabeth. Romano- no Natasha, Percy corrected himself, he'd been thinking of them as secret service people and had started calling them by their last names for some reason. He'd spent too long watching and waiting in that cafe. Anyway, she nodded.

They all got up and started walking to the ship. They'd landed it about a block away to be safe and not have too much demigod energy or smell or whatever (Percy had never really got that) near them. They already had 10 powerful demigods  _and_ the Oracle out of camp. It was a miracle they hadn't been attacked already.

They passed Nico and Will, who were sitting on a bench nearby, and they joined the group. Percy heard them introduce themselves to the Avengers as he walked at the front with Annabeth. He gave what her hoped to be a reassuring smile. She gave a small smile back, so he must have done something right.

They reached the Argo III, and climbed onboard.

"Why are we on a ship?" asked Tony, confused, "we aren't in water. Wait... is this another flying ship like the Argo II?" He seemed excited at that.

"This is the Argo III. It _is_ a flying ship, and is captained by Leo Valdez, who also designed and built it with his cabin mates." Annabeth took charge again. She rang the bell to tell the others that we were here, and then started to explain what we'd be doing. She's a good guide, thought Percy.

Jason, Leo, Frank and Hazel came up from below. They introduced themselves. First Jason, then Frank, then Hazel, and finally Le-

"HEY EVERYBODY, MY NAME IS LEO THE AWESOME AND I AM THE CAPTAIN OF THIS SHIP!!!" Leo yelled. He had set himself on fire, on purpose or by accident, Percy didn't know. He waved to the Avengers, who looked faintly surprised except for Tony, who was grinning at Leo.

"You built this?" he asked excitedly, "that's so cool. How do get the wood to not catch fire when you're burning. What do all of the things at the wheel do? What..." Tony went on and on. Leo looked ecstatic that his hero thought  _his_ ship was cool.

"Ok, let me show you  _everything_. Come on..." Leo led Tony away to his captain's wheel and started up the ship.

The Avengers looked over the rail with the demigods to see the ground rapidly falling away. Percy could see Hazel already looking a little green.

"What do they see?" wondered Steve, looking at the oblivious mortals below.

"I don't know," answered Percy truthfully, "I've always wondered that. Do they see, like, a giant bird, a hot air balloon, a plane? I don't know man."

Annabeth cleared her throat. She had all the others around her, ready to go for a tour of the ship. Percy hurriedly jogged over, Steve tearing his eyes away from their surroundings to come and listen to her too.

"Great. Now we're all here, let's go on a tour." Annabeth led the way downstairs.

"NEXT STOP, CAMP HALF BLOOD!!!" shouted Leo from the helm.


	4. A display of power

**Summary for the Chapter:**

> A monster attacks the ship when they are just outside of Camp Half-Blood. The Avengers get to see the demigods in action.

**Steve**

 

Steve still couldn't write believe that  _these_ were the greatest heroes of this age. Some of them were  _14._ Even _he_ hadn't joined the army at 14. But as he looked at them, he saw militance in their stance, posture, way of speaking. He saw that some of them were struggling, which he privately thought wasn't surprising - he never would have made it through what they had, and he saw which ones were burying their fears with distractions. He didn't blame them - that's what he had done when he had woken up.

It was just so unfair. He woke up, and he was told "We're not at war anymore. We won." but these  _children_ were still fighting, would always be fighting. Their war would never be over. 

Steve was thinking this as Annabeth led them around the ship. He took in the large eating and games room, the storage room, engine room (which Steve thought Tony seemed far too excited about), the bedrooms, and the stables. It was all high tech, run on magic and great engineering, and lived in by teenagers. He could tell. There was food everywhere, clothes on bedroom floors, books, belongings and weapons scattered everywhere - definitely children. 

As they were walking, Steve tried to remember who each and every Demigod was. He of course knew Percy, Annabeth, and Leo - each recognisable in their own way, and Piper, Hazel, Reyna, Nico and Will had introduced themselves to him early on. But there was also a big Chinese boy who might have introduced himself as Frank, a red head called Rachel - he remembered her last name, a blond boy who had to be Jason (the only one with glasses), a girl who had been talking to Clint all this time, who Steve thought might be Thalia, maybe? He was going to have to remember at some point - he din't want to get their names wrong.

 

Just then, as they were walking back up onto the deck, a huge judder ran through the ship. Half of them fell back down the stairs, and they all ran up into the open. Steve found himself staring slack-jawed straight at a monster that could only be a Griffin. With a panthers body and an eagles head, it stood at the prow of the ship, staring straight at them.

"Move!" yelled Percy, already holding his sword, "you can't help - your weapons can't hurt it."

Steve wisely ran to the side of the ship, dragging Bruce with him. Tony edged around the group of demigods and came to join them. Natasha and Clint, who had been at the back of the group, and had been bowled over by the falling people on the stairs, came onto deck, assessed the situation, and jogged over. Rachel, the Oracle, came over as well.

"Where's Thor?" asked Clint, "Can't he help them?"

"He just flew off the edge of the ship." replied Natasha.

"WHAT?" spluttered Steve, "He just left? Why?"

"I don't know," she said, "Oh wait, he's back."

Steve saw Thor fly up to the ship from below. He yelled to the demigods.

"There are about 20 more below us - do you want some help?"

"Nah... we're fine. Grifffin's aren't that dangerous," shouted Thalia.

She and Will had moved away from the group - she up the mast, in the crow's nest, ready to pick off the monsters with her bow, and Will away from the griffin, with the medical supplies at the ready.

Percy, Annabeth, Piper, Leo, and Nico moved to the left, and Reyna, Jason, Hazel, and Frank went to the right. Jason, Percy, Frank, Nico, Leo and Hazel were given a wider berth - Steve thought it might be because the others didn't want to get hit by their powers, but the others bunched together a bit more - maybe because Annabeth and Piper fought with knives, and Reyna could lend people her power if they needed it. They stood closest to the middle.

Frank transformed into a tiger, Leo went on fire, and Jason flew into the air. Steve was surprised to see Percy, Nico and Hazel not using their powers. Then he realised that Nico and Hazel's powers came from the earth, and they were in the sky, and Percy probably didn't need his if the Griffins weren't that dangerous. He  _was_ apparently the best sword fighter of the century.

Four more griffins landed on deck. They stood for a second, then screeched, and ran at the demigods. Frank the Tiger and Jason clashed with one, Annabeth and Piper with another. Thalia sent a rain of arrows onto a third, with Hazel casting blows at it while it was distracted. Reyna and Nico took on the fourth, attacking from both sides to keep it confused. Leo sent fire at the fifth, while Percy seemed to hang back from the fight a bit. Steve watched him carefully. He didn't seem to be the type to let his friends do all the work. Then he realised. Thor had said  _20_ griffins. This was only five.

Percy looked over the edge of the ship. A new griffin landed on deck and he gutted it quicker than Steve could see. His eyes widened. Two more griffins. One became headless, the other sent back to Tartarus with an ice spear in its chest. It was almost like watching a dance - Percys moves so controlled and powerful.

 

The first five creatures had been quickly destroyed. The children - although it wasn't quite fair to call them that, Steve thought - stood in the centre of the ship. They didn't even seem out of breath after killing eight monsters.

"I'll get the next five," called Thalia, "I can just blast them."

"Ok. Don't electrocute the ship," Leo shouted back.

"I can take the rest with Annabeth," Percy added, "You can all make sure that the Avengers are out of the way though. We wouldn't want them to get hurt."

The others nodded. Steve smiled to himself. He wasn't used to being the helpless one in fights like these - usually he was helping the civilians. 

The Avengers looked slightly wide eyed at the casual display of power that they had just seen. Percy had taken three monsters out on his own. And none of them had even broken a sweat!

When the rest of the demigods jogged over to them, leaving Thalia, who had climbed down the mast, Percy, and Annabeth standing guard. They went with them without trouble. They weren't the fighters here. 

Steve was just going down the steps when he saw the first flash of talons on deck. He turned for a second to see the three demigods fighting all of the griffins. There were a lot more than twenty. He half wanted to go and help, but then Percy let out a yell, and five of the creatures exploded. He decided they were fine.

 

The demigods led them back belowdecks to the Mess Hall. Leo immediately grabbed snacks, tossing them to Piper, Hazel, Rachel, Jason and Will. He threw one to Nico and Reyna as well, but they just looked at him stonily. He looked away first. 

Steve remembered Thor saying that Nico was a man out of time, just like him. Hazel too. He was secretly very excited about talking to them. He walked over to Nico hesitantly - he seemed like a person who didn't appreciate being snuck up on.

"Hi. I'm Steve," he said.

"I know," the kid replied, twisting his ring.

"I heard that you're from the 40s. Is that right?" Steve asked.

"Yeah. I'm from Italy though, not America, so I wasn't really on your side of the war at the start."

"Is it different now?" Steve asked, "I mean, the way people act, speak... you know."

"A little. When my sister and I came out of that hotel, we were sent straight to a boarding school, and then to Camp Half-Blood, so I never really spent that much time in the city though. I wouldn't really know all of the changes."

Nico seemed to be pretty comfortable talking, so Steve continued the conversation. They talked for about five minutes, until Percy, Annabeth, and Thalia came stumbling into the room, covered in monster dust, cuts, and water (maybe Percy's doing). They seemed to be in a good mood though, chatting, eating, and getting to know the Avengers.

Steve shook his head. He couldn't imagine fighting so often that killing that many monsters in the space of five minutes became so normal that no one mentioned it.

Life as a demigod seemed very weird. He couldn't wait to see their Camp. It would be an experience alright.


End file.
